How to Choose the Right RAM® Mount Ball Size for Your Device and Vehicle

Choosing the right RAM® Mount ball size is one of the most important steps when building your setup. A ball that’s too small for your device or environment can lead to drooping, vibration, and poor stability — and in Australia’s tough conditions, that can mean losing your device on the road or water.

This guide will explain the different B, C, and D size balls, how to choose the right one for your device, and which is best for different vehicles and environments.

Why Ball Size Matters

The RAM® Mount ball-and-socket system is designed for adjustability and shock absorption. Larger balls have more surface area and grip, meaning they can support heavier devices and handle more vibration. Smaller balls are lighter and more compact, perfect for smaller devices and tight spaces.

If you get the wrong size:

  • A too-small ball can slip or sag under weight.
  • A too-large ball can be overkill, adding unnecessary weight or bulk.

💡 Tip: In Australia, consider the extra vibration from corrugated roads, off-road driving, and marine chop — you may need to size up compared to US or EU recommendations.

The RAM® Mount Ball Size Chart

Ball Size

Diameter

Typical Load Capacity

Best For

Example Products

B Size

1" (25.4mm)

Up to ~0.9kg

Phones, GPS units, small cameras

RAM-B-201U Arm, RAM-HOL-UN7BU X-Grip

C Size

1.5" (38.1mm)

Up to ~1.8kg

Tablets, small laptops, heavy phones in rugged use

RAM-B-201U Arm, RAM-HOL-TAB8U Cradle

D Size

2.25" (57.15mm)

Up to ~2.7kg

Large tablets, laptops, marine radar units, industrial use

RAM-D-201U Arm

E Size

3.38" (85.85mm)

Over 3kg

Specialised heavy-duty gear

Special order only

(Load capacities vary depending on arm length and environment.)

Watch: How to Choose the Right Ball Size for Your Device

Want to know how to choose the right ball size for your device? This official video from RAM® Mounts walks you through everything you need to know to get started:


Choosing the Right Ball Size for Your Device

Phones

  • Best size: B Size (1" Ball)
  • Lightweight, compact, and ideal for everyday driving.
  • Works with the RAM® X-Grip, Quick-Grip, and form-fit phone cradles.
  • For motorbikes or boats, pair with a tether for extra security.

Tablets

  • Best size: C Size (1.5" Ball)
  • Larger surface area helps hold heavier devices steady.
  • Essential for off-road, tradie utes, and industrial forklifts.

Laptops & Large Screens

  • Best size: D Size (2.25" Ball)
  • Needed for mounting in trucks, mining vehicles, or marine setups where weight and vibration are high.

Matching Ball Size to Your Vehicle & Environment

Cars & 4WDs

  • Phones: B size + standard arm.
  • Tablets: C size for dashboard or floor mounts.
  • Consider Australian vibration conditions — off-roaders may benefit from C size even for large phones.

Motorbikes & Scooters

  • Phones: B size with tether.
  • Short arm reduces vibration.
  • Use waterproof cradles for wet weather riding.

Boats & Marine Use

  • Phones & GPS: B or C size with stainless hardware.
  • Fishfinders & Radar Displays: C or D size.
  • Always rinse saltwater gear after use.

Industrial & Mining Vehicles

  • Tablets & Laptops: C or D size with long arm for reach.
  • Heavy-duty bases (drill-down or clamp) are essential for stability.

Common Mistakes to Avoid

  1. Mixing ball sizes — B, C, and D parts aren’t interchangeable. All components in your setup must match the ball size.
  2. Overloading small balls — a heavy tablet on a B size arm will droop over time.
  3. Over-tightening — this can deform the rubber ball and reduce grip.
  4. Ignoring environment — vibration, heat, and humidity can affect performance, especially in Australia.

Quick Reference: Ball Size Selector

  • B Size (1") → Best for small devices & low-vibration environments.
  • C Size (1.5") → Best for tablets & medium-to-high vibration.
  • D Size (2.25") → Best for large devices & extreme conditions.

View All B Size Mounts | View All C Size Mounts | View All D Size Mounts

Pro Tips for Longer-Lasting Performance

  • Clean rubber balls regularly with mild soap and water to restore grip.
  • Use thread locker (blue Loctite) for bolts in high-vibration vehicles.
  • Choose UV-resistant components if mounting outdoors long-term.
  • Keep a spare arm or cradle in your glovebox for quick swaps on the road.

Need Help Choosing?

If you’re unsure, our team can help match the perfect ball size to your device and vehicle.

📞 Call us on 07 3067 2130
📧 Email sales@mounts.net.au

Or learn more from this guide: How to Set Up Your RAM® Mount: The Complete Beginner’s Guide

 

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